Scalings of Ion-Temperature-Gradient-Driven Anomalous Transport in Tokamaks.

Results are presented from the first systematic nonlinear gyrokinetic simulation study of the scalings and parameter dependences of toroidal ion-temperature-gradient-driven (ITG) turbulence and transport in large magnetic-fusion-relevant tokamaks. Such simulations are made possible by significant advances in computational physics algorithms which are summarized. The simulated ion-thermal transport rates have clear {open_quote}{open_quote}gyroreduced Bohm{close_quote}{close_quote} scaling and are too low to account for the anomalous transport seen in the outer half of some TFTR {ital L}-mode discharges, indicating that additional mechanisms, such as nonadiabatic-electron effects, are operative. {copyright} {ital 1996 The American Physical Society.}